Connector parts are produced within tolerance and at lower cost on a CNC sliding head automatic and economical batch sizes are 200-off and less.

A recent convert to CNC sliding-head mill-turning, Hampshire, UK subcontractor Croft Engineering supplies a local electronic equipment manufacturer with connector parts that were previously produced by another contract machinist in the UK to a lower standard on cam automatics. For years the customer thought that the poor quality was normal; then it approached a subcontractor in India to try to obtain a better price and was disappointed at the quality of the samples that came back. The parts are now produced within tolerance and at lower cost on Croft's multi-axis Star SR-32J sliding head automatic lathe, according to Jason Mortara, joint owner of Croft with his parents, Paul and Judy.

Furthermore, economic batch size is down to 200-off or less and delivery is fast, factors that are of considerable benefit to the customer, as it specialises in bespoke electronic instruments for niche markets.

The arrangement has worked so well that in the first seven months, over 50 different styles and sizes of connector from 6 to 16mm diameter and up to 30mm long had been produced on the Star.

What was originally envisaged as GBP 15,000 of business annually will in the 12 months to March 2007 be at least double that figure.

So pleased is the customer that its proprietor has written a letter to Mortara stating, 'The improved quality and delivery times from Croft, together with keener prices, have enabled us to give a better service to our existing clients and to gain new business from our competitors.' Croft found that there was little money to be made using its manually operated machine tools, so a few years ago the company invested in a CNC chucking lathe and milling machine.

However, staff costs were high because most parts still needed subsequent operations, and overheads such as rates and electricity were climbing.

Competition was fierce and profit margins remained slim.

It became obvious that a change of direction was needed.

Enquiries were being received for components that were more suitable for sliding-head machining.

So a study was carried out which showed that the best lathe for the type of work under discussion was the Star SR-32J.

An investment of over GBP 100,000 in a machine tool is a big step for a family-owned company, but Croft was getting all the right signals from potential customers, such as the electronic equipment manufacturer which happened to call in for a simple manual job to be done, and a press shop in Oxford that needed low cost, threaded inserts in quantities of 4,000-off.

Discussions with these two prospects, coupled with on-going machining of concrete drill adapter components up to 32mm diameter for another party, eventually persuaded Croft to take the plunge.

A second-hand sliding head machine was rejected, as Croft was new to the technology and needed the reassurance of having a comprehensive service package including warranty, cycle time estimates, programs, training, tooling advice and telephone helpdesk.

'All have been readily forthcoming from Star GB,' said Paul Mortara.

'It has been a very good experience.

We were comfortable with the Star lathe, Fanuc control and FMB bar magazine three months after installation - earlier than we thought.' He added: 'Star even recommended the finance house, which was able to offer good terms as it is familiar with the higher-than-average residual value of the machines.' Since the SR-32J was installed in March 2006, the situation at Croft Engineering has been transformed.

Few subcontractors in the area have such a capable mill-turning facility, so competition is much less.

Once set, the bar-fed machine works around the clock with minimal attendance during the day and unmanned overnight, turning out top quality components.

Paul Mortara sums up the advantage of the SR-32J using the example of the concrete adapter parts that the firm has been making since 1993.

Initially the components were machined entirely manually; then using the CNC chucker followed by manual drilling, tapping and hexagon milling on three separate machines; and finally in automatic, 'one-hit' cycles on the Star.

Where it used to take approximately 40h to machine a batch of 500-off, it now takes a third of the time with very little manual intervention, added to which quality is greatly improved.

Full use is made of the SR-32J's capabilities.

Tolerances within 10 micron are routinely held, whereas that was far more difficult on Croft's other production plant.

All parts are transferred to the opposed sub spindle for reverse endworking and around half undergo driven tool operations.

Of the other 50% of components, some can be extremely simple, prompting people to suggest one does not need a CNC slider to produce them.

Croft's experience is that these are machined just as cost effectively as more complex parts.

Jason cited the example of valve guides they produce in various sizes for classic cars.

Each guide requires only a short cycle, but all are very price-sensitive.

The job was referred from another subcontractor that was unable to be competitive.

Croft's view is that even if a majority of work is relatively simple and only the occasional part requires a complicated machining sequence, there is no problem justifying the purchase of a CNC sliding head automatic.

Unit production cost will always be an issue for customers, yet a subcontractor must be able to amortise a machine tool over a reasonable period.

One method that Croft uses to assist in meeting these conflicting needs is to suggest to a customer that design changes are made to a component so that it can be produced in a shorter cycle time on the Star, and perhaps in one operation rather than in two or three.

Another cost-down technique is to offer to fulfill a non-urgent order during the following week, say, when the correct size and type of bar is scheduled to be in the magazine.

This saves set-up time and reduces the price per part.

Paul Mortara concluded by commenting, 'Manufacturers in the UK often do not want to have their components made abroad, but feel that they are forced to by customers demanding ever lower prices.

Now there is another option to consider.' He said: 'Highly automated, multi-tasking machine tools like the Star are the answer to keeping work in Britain.

We will probably buy a 16mm or 20mm model next, which will be even more economical at producing smaller parts and increase our competitiveness further.'